BAGHDAD — A bomb ripped through a crowded market in Baghdad's main Shiite district on Wednesday, killing at least 69 people and wounding more than 100 less than a week before a deadline for U.S. combat troops to leave Iraq's urban areas.

A series of blasts this week have killed more than 160 people, as U.S. and Iraqi officials warned they expected more violence before the U.S. withdrawal from cities.

The 7 p.m. blast at the market appeared to be timed to maximize casualties by striking shoppers buying food for their evening meal.

The explosives were loaded on a motorized pushcart and shrapnel was blown more than 600 yards away, a police officer said.

The explosion also set some shops ablaze in the market.

Violence expected to escalate
U.S. and Iraqi officials have warned that violence would likely increase before the June 30 deadline for most American troops to pull back from urban areas — the first stage of a full withdrawal by the end of 2011.

Brig. Gen. Steve Lanza, a U.S. military spokesman, said earlier Wednesday that the high-profile bombings were an effort to rekindle sectarian violence that pushed the country to the brink of civil war.

As part of the withdrawal, American commanders on June 20 turned over control of a key base on the edge of Sadr City. The base served as the hub for all operations in the sprawling slum, which was a militia stronghold where fierce clashes took place before a U.S.-backed government crackdown and a cease-fire.

Four days earlier, a truck bombing killed 82 people in a mainly Shiite town near the northern city of Kirkuk, which was the deadliest bombing so far this year.

Back-to-back suicide bombings by female attackers also killed 71 people outside a Shiite shrine in Baghdad on April 24.

Blasts overshadow plans for holiday
The Iraqi government on Tuesday declared a public holiday to mark next week's withdrawal of U.S. combat troops from Baghdad and other cities.

American forces already have begun pulling back from outposts inside the cities ahead of a June 30 deadline, the first phase of a full withdrawal by the end of 2011.

Government spokesman Ali al-Dabbagh said Tuesday that ceremonies will be held on Monday and the deadline itself will be a public holiday, although students will still have to take their final exams as scheduled.

The announcement comes days after Prime Minister Nouri al-Maliki called the U.S. withdrawal from the cities a "great victory," despite fears that violence will increase after the Americans become less visible.

The stakes are high for al-Maliki's Shiite-led government to prove it is capable of taking care of its people ahead of parliamentary elections scheduled for Jan. 30.

Iraqi forces ready?
The recent high-profile bombings have raised concerns about the readiness of Iraqi forces to provide security around the country without the immediate help of the U.S. troops remaining in Iraq.

According to a security pact that came into force in January, most of the American troops will be housed on large bases outside the capital and other cities — unable to react unless called on for help by the Iraqis.

Many Iraqis oppose the presence of the Americans, whom they consider an occupying force, and military officials hope the withdrawal timeline will help stem support for the insurgency.

Separately, an Iraqi civilian was killed and another injured Tuesday morning when a U.S. vehicle hit their motorcycle that had stalled on a road near the U.S. detention facility Camp Bucca in southern Iraq, the military said.

Lt. Col. Kevin Olson, a spokesman for U.S. forces in southern Iraq, said it was a "tragic accident."